[libcxx-commits] [libcxx] Fix the LWG 3568 test for basic_istream_view (PR #215589)

[Iskandar Emomzoda via libcxx-commits]

================
@@ -39,10 +39,8 @@ void test() {
 
   // LWG 3568. basic_istream_view needs to initialize value_
   {
-    auto iss = make_string_stream<CharT>("");
-    std::ranges::basic_istream_view<int, CharT> isv{iss};
-    auto iter = isv.begin();
-    assert(*iter == 0);
+    static auto fn_local_iss = make_string_stream<CharT>("");
+    [[maybe_unused]] constexpr auto isv = std::views::istream<int>(fn_local_iss);
----------------
iskandarem wrote:

Do you mean something like this 
```cpp 
{
    auto iss = std::stringstream("42");

    std::ranges::basic_istream_view<NoopExtraction, CharT> isv{iss};
    auto iter = isv.begin();
    assert((*iter).n_ == 0);
    return 0;
}
```
https://godbolt.org/z/zoWMszMTs

https://github.com/llvm/llvm-project/pull/215589